The aim of this project is to assess the effect of maturation and sleep on the control of respiration in full term and premature infants. We plan to measure the ventilation and the ventilatory response to inhaled carbon dioxide in full term and premature infants while awake and during various stages of sleep using non-invasive techniques that involve no patient risks. Serial measurements will be made at monthly intervals on each subject from birth to 3 months of ages. The barometric method will be used to measure ventilation to eliminate the effect of tactile stimuli on ventilation. The recording of the electroencephalogram (EEG) and rapid eye movements (REM) will be used for the staging of sleep. Our objective is to study the effect of sleep and alterations in the stage of sleep on ventilation in the first three months of life and to characterize any change in the respiratory control mechanism as maturation of the central nervous system takes place. We believe that this study will be of importance in furthering our understanding of the pathogenesis of (1) the sudden infant syndrome (SIDS) since this syndrome has its peak incidence during the sleeping hours at 3 months of age, (2) recurrent neonatal apnea, and (3) periodic breathing in infants. It may also help us to understand the relationship between neurophysiologic maturation as assessed by the EEG and REM analysis and diural variations in ventilation.